Extending zfsboot.c to allow selecting filesystem from boot.config

[Andriy Gapon]

on 23/11/2011 00:25 Andriy Gapon said the following:
> Unfortunately the logs that you captured do not reveal a source of the problem.
> I think that it would make sense to set a breakpoint at the zfs_mount function
> ('b zfs_mount').  When the program stops at a break point, you can then 'step'
> through the code.  Then examine all arguments upon function calls and local
> variables at the interesting places.  For variables that are pointers please
> print their dereferenced value (like 'p *x').  This could be time consuming.
> 
> Some more straightforward things to (re-)test.
> First, are you absolutely sure that the problem never happens without the patch?
>  Could you please retest that?  Please do not touch anything under /boot, just
> recompile zfsboottest with the patch reverted and run it a few time.
> Then, could you please test the patch with the code from head?  Again, no need
> to change you real boot blocks, just checkout sys/boot from head, patch it,
> recompile zfsboottest and test it.

Or another idea is to use valgrind ... which I have actually done myself and
found the problem.
While I am working on a proper solution, please try this quick patch:
http://people.freebsd.org/~avg/zfsboot.read_mos.patch

-- 
Andriy Gapon